#include <stdio.h>
#include <math.h>
double a, b, c, l;

double area(double a, double b, double c)
{
	double p;
	p = (a+b+c)/2;
	p = p*(p-a)*(p-b)*(p-c);
	return sqrt(p);
}

int main()
{
	double r, R, pi, L, s;
	int icase=0;
	pi = asin(1)*2;
	while (scanf("%lf%lf%lf%lf", &a, &b, &c, &l)!=EOF)
	{
		if (a<1e-5 && b<1e-5 && c<1e-5 && l<1e-5) break;
		L = a + b + c;
		s = area(a, b, c);
		r = 2*s/L;
		R = r*(L-l)/(L-2*pi*r);
		printf("Case %d: ", ++icase);
		if (l <= 2*pi*r)
			printf("%.2lf\n", l*l/4/pi);
		else 
			printf("%.2lf\n", pi*R*R + s*(R-r)*(R-r)/(r*r) - R*L*(R-r)/r);
	}

	return 0;
}